茶多酚对D-半乳糖与Aβ25-35诱致脑神经细胞凋亡的保护作用

目的：研究茶多酚（tea polyphenols，TP）干预D-半乳糖与Aβ25-35诱导小鼠脑神经细胞凋亡作用，并探讨其抗氧化和调节细胞内钙稳态作用与其抑制神经细胞凋亡之间的作用关系。方法：D-半乳糖（120mg／kg·d^-1）皮下注射给药12周，并在第7周时，侧脑室缓慢注射Aβ25-35（icv，4nmol），造成老年性痴呆动物模型，并于造模开始时灌胃给予TP12周。采用LW-Ⅱ型水迷宫仪测定小鼠学习记忆情况，并分别取其脑、肝脏组织和血清测定超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量；Fura-2／AM负载法测定细胞浆钙离子浓度；流式细胞仪检测脑神经细胞凋亡。结果：D-半乳糖与Aβ25-35共同处理可诱导小鼠脑神经细胞凋亡发生率达31．5％，同时血清、肝脏和脑组织MDA含量明显增高，SOD活性明显降低，红细胞和脑细胞内钙离子浓度明显高于正常对照组，并伴有学习记忆功能障碍。TP中剂量（250mg／kg）和高剂量（625mg／kg）处理后，明显降低模型动物脑神经细胞凋亡发生率（18．6％和12．6％），增加SOD活性，降低MDA含量和红细胞、脑细胞内钙离子浓度，对模型动物的学习记忆障碍有明显的改善作用。结论：TP可抑制D-半乳糖与Aβ25-35诱导的脑神经细胞凋亡，并明显改善模型小鼠学习记忆能力，其作用可能与提高全身性抗氧化能力，改善氧化应激损伤引起的细胞内钙超载有关。

Determination of β-amyloid peptides in vitro aggregation process by electrochemistry

An impedimetric sensor(EA/mAb/CeZnO/GCE)for detecting β-amyloid peptides(Aβ)was successfully constructed by synthesizing ceria doped zinc oxide(CeZnO)nanoparticles to modify the glassy carbon electrode(GCE)for immobilizing the antibody mAb,and blocking the unbound carboxyl sites with ethanolamine(EA).The sensor exhibited a linear detection range of 10–100 pM and a detection limit of 1.7 pM(S/N=3),and the relative standard deviations(RSDs)of the inter-electrode and intra-electrodes were less than 3.0%.After it was stored at 4℃ for 2 d,its impedance value was 101.6% of original impedance response.The sensor was used to measure the remaining content of Aβ incubated in vitro.The results showed that after incubation for 48 h and 60 h,the content of aggregated Aβ(oligomers and fibers)almost unchanged,reaching about 90%.This method had the advantages of time-saving,simple procedure,economical,excellent conductivity,good reproducibility and stability.